Peculiarities of the Far-Infrared Reflection Spectra of the Doped Lead-Tin Tellurides Revealing the Persistent Photoconductivity Effect

1990 ◽  
Vol 216 ◽  
Author(s):  
Aleksander I. Belogorokhov ◽  
Ivan I. Ivanchik ◽  
Dmitriy R. Khokhlov ◽  
Zoran V. Popovich ◽  
Nebojsha Romchevich
Keyword(s):  
Low Temperatures ◽  
Far Infrared ◽  
State Transitions ◽  
Coordinate Space ◽  
Persistent Photoconductivity ◽  
Reflectivity Spectra ◽  
Infrared Reflection ◽  
State Position ◽  
The One ◽  
Configuration Coordinate

ABSTRACTWe measured the far-infrared reflectivity spectra of PbTe(Ga) and Pb1−xSnxTe(In) - materials revealing the Persistent Photoconductivity effect at the low temperatures T<Tc; Tc≈80K and 25K, respectively-The reflectivity spectra display the singuliarity nearby the plasmon-phonon minimum. The spectra may be fitted satisfactory by means of the introduction of an additional oscillator into the dispersion relation. The result is interpreted in the framework of the model taking into account the temperature change of the one-electron metastable impurity state Position in the configuration-coordinate space. The oscillator corresponds to the two-electron - one-electron state transitions. Some previously unexplained results find the satisfactory interpretation in the framework of the model Proposed.

Far Infrared Reflection Spectra of AgCl, AgBr, and AgI at Low Temperatures

1968 ◽  
Vol 7 (6) ◽  
pp. 1159 ◽  
Author(s):  
Armand Hadni ◽  
Jacques Claudel ◽  
Pierre Strimer
Keyword(s):  
Low Temperatures ◽  
Far Infrared ◽  
Reflection Spectra ◽  
Infrared Reflection

FAR-INFRARED PROPERTIES OF (TMTSF)2ClO4AT LOW TEMPERATURES

1983 ◽  
Vol 44 (C3) ◽  
pp. C3-867-C3-872 ◽  
Author(s):  
H. K. Ng ◽  
T. Timusk ◽  
K. Bechgaard
Keyword(s):  
Low Temperatures ◽  
Far Infrared

scholarly journals On the measurement of the ratio of the specific heats using small volumes of gas.—The ratios of the specific heat of air and of hydrogen at atmospheric pressure and a temperatures between 20°C. and —183°C

1925 ◽  
Vol 107 (743) ◽  
pp. 510-543 ◽  
Keyword(s):  
Systematic Error ◽  
Low Temperatures ◽  
Room Temperature ◽  
Expansion Chamber ◽  
Small Vessels ◽  
Specific Heats ◽  
Large Expansion ◽  
Before And After ◽  
The One ◽  
Chamber Capacity

Introduction .—In nearly all the previous determinations of the ratio of the specific heats of gases, from measurements of the pressures and temperature before and after an adiabatic expansion, large expansion chambers of fror 50 to 130 litres capacity have been used. Professor Callendar first suggests the use of smaller vessels, and in 1914, Mercer (‘Proc. Phys. Soc.,’ vol. 26 p. 155) made some measurements with several gases, but at room temperature only, using volumes of about 300 and 2000 c. c. respectively. He obtained values which indicated that small vessels could be used, and that, with proper corrections, a considerable degree of accuracy might be obtained. The one other experimenter who has used a small expansion chamber, capacity about 1 litre, is M. C. Shields (‘Phys. Rev.,’ 1917), who measured this ratio for air and for hydrogen at room temperature, about 18° C., and its value for hydroger at — 190° C. The chief advantage gained by the use of large expansion chambers is that no correction, or at the most, a very small one, has to be made for any systematic error due to the size of the containing vessels, but it is clear that, in the determinations of the ratio of the specific heats of gases at low temperatures, the use of small vessels becomes a practical necessity in order that uniform and steady temperature conditions may be obtained. Owing, however, to the presence of a systematic error depending upon the dimensions of the expansion chamber, the magnitude of which had not been definitely settled by experiment, the following work was undertaken with the object of investigating the method more fully, especially with regard to it? applicability to the determination of this ratio at low temperatures.

scholarly journals The principal magnetic susceptibilities of neodymium sulphate octahydrate at low temperatures

1939 ◽  
Vol 170 (941) ◽  
pp. 266-271 ◽  
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Energy Levels ◽  
Constant Factor ◽  
The Other ◽  
Crystalline Field ◽  
Cubic Symmetry ◽  
The Subject ◽  
The Difference ◽  
The One

The magnetic and other related properties of neodymium sulphate have been the subject of numerous investigations in recent years, but there is still a remarkable conflict of evidence on all the essential points. The two available determinations of the susceptibility of the powdered salt at low temperatures, those of Gorter and de Haas (1931) from 290 to 14° K and of Selwood (1933) from 343 to 83° K both fit the expression X ( T + 45) = constant over the range of temperature common to both, but the constants are not the same and the susceptibilities at room temperature differ by 11%. The fact that the two sets of results can be converted the one into the other by multiplying throughout by a constant factor suggested that the difference in the observed susceptibilities was due to some error of calibration. It could, however, also be due to the different purity of the samples examined though the explanation of the occurrence of the constant factor is then by no means obvious. From their analysis of the absorption spectrum of crystals of neodymium sulphate octahydrate Spedding and others (1937) conclude that the crystalline field around the Nd+++ ion is predominantly cubic in character since they find three energy levels at 0, 77 and 260 cm. -1 .* Calculations of the susceptibility from these levels reproduce Selwood’s value at room temperature but give no agreement with the observations-at other temperatures. On the other hand, Penney and Schlapp (1932) have shown that Gorter and de Haas’s results fit well on the curve calculated for a crystalline field of cubic symmetry and such a strength that the resultant three levels lie at 0, 238 and 834 cm. -1 , an overall spacing almost three times as great as Spedding’s.

Determining the Free Carrier Density in Cd x Hg1–xTe Solid Solutions from Far-Infrared Reflection Spectra

2017 ◽  
Vol 51 (13) ◽  
pp. 1732-1736
Author(s):  
A. G. Belov ◽  
I. A. Denisov ◽  
V. E. Kanevskii ◽  
N. V. Pashkova ◽  
A. P. Lysenko
Keyword(s):  
Solid Solutions ◽  
Carrier Density ◽  
Far Infrared ◽  
Free Carrier ◽  
Reflection Spectra ◽  
Free Carrier Density ◽  
Infrared Reflection
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